/**
 * Created with IntelliJ IDEA.
 * Description:
 */

class Number{
    public int num;
}

public class Main {
    public static void swap(Number number1,Number number2){
        int tmp = number1.num;
        number1.num = number2.num;
        number2.num = tmp;
    }

    public static void main(String[] args) {
        Number number1 = new Number();
        number1.num = 10;
        Number number2 = new Number();
        number2.num = 20;
        swap(number1,number2);
        System.out.println(number1.num+" "+number2.num);
    }
}
